RT Journal Article SR Electronic T1 P480 Enhanced prevalence of Chlamydia trachomatis DNA in clinical samples of patients with STIs co-infection JF Sexually Transmitted Infections JO Sex Transm Infect FD BMJ Publishing Group Ltd SP A223 OP A223 DO 10.1136/sextrans-2019-sti.562 VO 95 IS Suppl 1 A1 Feodorova, Valentina A1 Zaitsev, Sergey A1 Saltykov, Yury A1 Grashkina, Irina A1 Gaydos, Charlotte A1 Quinn, Thomas A1 Motin, Vladimir YR 2019 UL http://sti.bmj.com/content/95/Suppl_1/A223.2.abstract AB Background Chlamydia trachomatis (CT) is one of the most commonly diagnosed asymptomatic bacterial cause among sexually transmitted infection (STI) worldwide. We assessed the prevalence of CT in random STI patients to evaluate the presence of CT as either a single infection or in co-infection with other STI.Methods A total of 422 urogenital samples were collected from patients who attended the Diagnostic Centre in Saratov Region to be tested for specific DNA of CT and other STIs (Neisseria gonorrhoeae/Trichomonas vaginalis/Mycoplasma hominis/Mycoplasma genitalium/Human papillomavirus (HPV 16/18)/Cytomegalovirus/Herpes simplex virus (HSV 1/2)/Candida albicans/Gardnerella vaginalis/Ureaplasma species. Each clinical sample was carefully screened with the use of commercial kits, either as conventional PCR targeting CT plasmid, or real-time multiplex set (Vector-Best, Russia) validated further by additional confirmatory PCR for the CT-positive samples.Results CT was detected in 17/194 (4,02%) patients who were screened only for the presence of CT DNA (194/422, 45,97%). However, when all 422 patients were systematically screened for CT, along with all other STIs, CT infections were significantly higher (about 4-fold larger) in the patients with other STIs (70/422, 16.58%). Moreover, 56/70 (80%) CT DNA samples were successfully genotyped as CT genovars: E (50%), G (21,42%), D (17,85%), J (5,35%) and K (3,57%).Conclusion Chlamydial asymptomatic infection cases can be frequently masked by clinical symptoms of other STIs. Diagnostic testing for multiple STIs should provide a broader diagnostic coverage for asymptomatic CT patients in order to improve significantly CT early detection, prevention of transmission, and treatment strategies.Disclosure No significant relationships.